Various grinding apparatus have been disclosed in the patent literature for grinding a workpiece to a desired profile. such apparatus commonly make use of a pantograph assembly or the like to move the grinding wheel to correspond to the movement of a stylus along a template or guide. Examples of such apparatus are shown in U.S. Pat. Nos. 2,164,169 (Wohlforth), 2,248,446 (Wohlforth), 2,521,958 (Angerby et al), 2,553,099 (Lowber et al), and 2,600,402 (Griffin). Various United States patents have even disclosed the use of optical means to provide an image of the profile of the workpiece during the grinding operation. Examples of such optical means are found in such U.S. patents as U.S. Pat. Nos. 2,164,169 (Wohlforth), 2,248,446 (Wohlforth), 2,372,470 (Bergstrom et al), 2,465,038 (Reams), 2,614,368 (Polk et al), 3,039,239 (Banko) and 3,143,831 (Banko).
Commercially available profile grinding apparatus commonly utilize a pantograph to carry a grinding wheel along a path corresponding to the profile of a template or a guide. For example Fritz Studer Limited of Clockenthal-Thun, Switzerland produces a profile grinding machine using a pantograph-parallelogram assembly for carrying a grinding wheel to the profile of a template. The grinding wheel is moved in a horizontal plane in response to the movement of a stylus about the periphery of the template. The workpiece to be ground is mounted on a table which reciprocates vertically while the grinding wheel remains stationary to profile the workpiece to the contour of the template. Other manufacturers offer similar type profile grinding apparatus, while various manufacturers, such as the Cinncinnati Milling Machine Co., of Cinncinnati, Ohio, Wickman, Limited of Coventry England, and Eric R. Bachmann Company, Inc. of Long Island City, N.Y., offer grinding apparatus having means for optically displaying the profile of the workpiece being ground.
Optical devices themselves are commercially available for use with machining apparatus for projecting an image of the workpiece onto the screen. Such devices are commonly referred to as "shadowgraphs" since the image projected represents the shadow of the profiled workpiece. Shadowgraphs are commonly arranged to display the desired profile of the workpiece to be ground, via the use of an overlay. With such devices the machinist can readily compare the shape of the workpiece during the machining operation to the desired profile in order to precisely contour the workpiece.
While shadowgraphs and other similar optical devices have great potential for profile grinding applications, the use of such devices on relatively simple pantograph-mounted grinding apparatus is not without limitation. The most substantial limitation is that it is difficult to maintain a focused image of the workpiece during the grinding operation since the workpiece is moved by the vertically reciprocating table with respect to the fixed position, pantograph-mounted grinding wheel. Some grinding apparatus have attempted to overcome this problem by mounting the optical viewing device for corresponding movement with the pantograph. See for example the U.S. Pat. Nos. 2,164,169 (Wohlforth) and 2,248,446 (Wohlforth).
Accordingly, it is a general object of the instant invention to provide a profile grinding apparatus which overcomes the disadvantages of the prior art.
It is a further object of the instant invention to provide a profile grinding apparatus having means for displaying an image of the profile of the workpiece during operation.
It is a further object of the instant invention to provide a profile grinding apparatus including grinding means carried by a pantograph assembly and arranged for vertical reciprocation.
It is still a further object of this invention to provide profile grinding apparatus including means for displaying a constantly focused image of the profile of the workpiece during grinding and which apparatus is simple in construction.
It is still a further object of this invention to provide profile grinding apparatus including pantograph means for moving a grinding assembly through a path corresponding to the contour of the template or to the movement of a template holding table.
It is yet a further object of this invention to provide profile grinding apparatus capable of grinding a bevelled edge on a workpiece.